Electrical switching device, relay and electrical apparatus comprising same

ABSTRACT

The electrical switching device comprises at least a first part comprising at least a first magnetizable element and a first contact zone associated with said first magnetizable element, and at least a second movable part comprising at least a second magnetic element and a second contact zone associated with said second magnetic element. The first or second magnetic element comprises at least one permanent magnetization part to keep the first electrical contact closed and to exert a contact pressure between the first and second contact zones when the movable part is in a first stable position. The electromagnetic relay and/or electrical apparatus comprise electrical contact inputs and control inputs connected to a switching device comprising electromagnetic control coils.

BACKGROUND OF THE INVENTION

The invention relates to an electrical switching device comprising atleast one electrical contact able to be kept in a stable position bymagnetic means. The invention also relates to an electromagnetic relaywith at least two stable states comprising at least a first and a secondelectrical contact inputs, control inputs, and at least one suchswitching device. The invention also relates to an electrical apparatuscomprising at least a first and a second electrical contact input, andat least one such switching device.

State of the Art

Known switching devices, integrated in particular in relays andelectrical switchgear apparatuses such as switches, comprise electricalcontacts controlled in particular by a manual control means or anelectromagnetic coil. Generally speaking, the electrical contactscomprise a fixed part and a movable part to open or close an electriccircuit. The electrical contacts are kept in an open or closed positionin certain apparatuses by a mechanism. In bistable relays,electromagnets are associated with magnets to keep the contacts instable positions.

FIG. 1 shows a bistable relay comprising a contact block 1 with a fixedpart 2 having one or more electrical contact pads 3, and a movable part4 comprising a flexible blade 5 bearing at least one electrical contactpad 6. The contact block of FIG. 1 is a changeover switch with twoelectrical contacts connected to connection terminals 7. The contactblock 1 is actuated on its movable part by a bistable electromagneticdevice 8 comprising a fixed part 9 and a movable part 10 mechanicallyconnected to said contact block. The electromagnetic device 8 comprisesa magnetic circuit 11 formed in the fixed part 9 by a magnetic material12 and a permanent magnet 13, and in the movable part 10 by a blade heldby a spring 14. An electromagnetic coil 15 wound onto the magneticmaterial of the fixed part actuates movement of the movable part 10. Ifa current flows in a first direction in the coil 15, the movable part isattracted towards the fixed part and the magnetic circuit closes. Thepermanent magnet 13 then keeps the magnetic circuit closed even if thecurrent in the coil is, interrupted. If a current pulse is injected in asecond direction opposite to the first direction, the action of themagnet is cancelled by a reverse magnetic field generated by the coil,and the blade is then urged by the spring 14 back to an open magneticcircuit position. The strength of the magnet 13 is not sufficient toattract the blade held by the spring in the open circuit position. Abistable relay of this type is described in particular in the Patent EP0,686,989 B1.

FIG. 2 shows a bistable relay comprising a contact block 1 similar tothat of FIG. 1 actuated by an electromagnetic device 16 having a movablepart 17 with a permanent magnet 18. The fixed part generally comprises afirst or a second magnetic circuit 19 and 20 controlled byelectromagnetic coils 21 and 22 enabling the magnet to be moved towardsthe first or the second magnetic circuit. When the magnet is in contactwith one of the magnetic circuits, the magnetic induction of said magnetenables the movable part to be kept in a stable state. Thus, themagnetic circuit which retains the movable part with the magnet becomesa closed magnetic circuit and the other magnetic circuit is open.Certain devices of this type comprise a single electromagnetic controlcoil and different arrangements of the fixed part. Bistable devices withmovement of a movable part bearing the magnet are described inparticular in the Patents EP 0,272,164 B1 and FR 2,358,006.

Known switching devices, integrated in particular in bistable relays,enable weak electric currents to be switched or broken in goodconditions. When the currents to be switched are strong, for exampleseveral Amperes, known devices are generally bulky. In addition, thecontact blocks have a large temperature rise and the magnetic circuitshave to exert strong forces to move the movable parts. Such switchingdevices are difficult to integrate in electrical apparatuses of smalldimensions able to be actuated manually.

SUMMARY OF THE INVENTION

It is one object of the invention to provide an electrical switchingdevice enabling a good electric current conduction, a good electriccircuit switching or interruption and/or having reduced dimensions orvolume. It is also an object of the invention to provide a relay and anelectrical apparatus comprising such a device.

A switching device according to the invention comprises:

at least a first part comprising at least a first magnetizable elementand a first contact zone associated with said first magnetizableelement,

at least a second movable part comprising at least a second magneticelement and a second contact zone associated with said second magneticelement, said second movable part having at least a first stableposition to keep a first electrical contact closed between the first andsecond contact zones and a second stable position to keep said firstelectrical contact open, and

electromagnetic actuating means acting on the second movable part tomake the latter change position and comprising at least a firstelectromagnetic coil wound onto at least a first magnetizable element ofthe first part to act in attraction or repulsion on at least a secondmagnetic element of the second movable part and to perform a change ofstable state of said second movable part,

the first or second magnetic element comprising at least one permanentmagnetization part to keep the first electrical contact closed and exerta contact pressure between the first and second contact zones by amagnetic attraction exerted between the first and second magneticelements when the movable part is in its first stable position.

Advantageously, the electromagnetic actuating means comprise at least asecond electromagnetic coil wound onto at least a third magnetizableelement of the first part to act in attraction or in repulsion on atleast a second magnetic element of the second movable part and toperform a change of stable state of said second movable part.

Advantageously, the first and second electromagnetic coils are designedto be controlled by electrical pulses to generate reverse magneticfields performing a repulsion and an attraction and to make the stableposition of the second movable part change between a first and a secondstable position closing at least one electrical contact between acontact zone of the first part and a contact zone of the second movablepart.

Advantageously, the first and second electromagnetic coils are designedto be controlled by electrical pulses to generate magnetic fields of thesame direction performing two repulsions and to position the secondmovable part in a third stable position where the contact zones of thesecond movable part are not in electrical contact with the contact zonesof the first part.

Advantageously, the first part comprises a third magnetizable element tokeep the second movable part in the second stable position.

In a preferred embodiment, the second movable part comprises at leastone permanent magnet arranged in proximity to a contact zone.

Advantageously, the second movable part is composed of a materialcomprising a mainly permanent magnetization part.

Preferably, the permanent magnetization part or the permanent magnethave a magnetic induction greater than 1 tesla.

Advantageously, the second movable part has an elongate shape able topivot and comprises at least one contact zone and one magneticattraction zone towards at least one end. Preferably, the second movablepart comprises at least one contact zone and one permanent magnet at afirst end and at a second end.

In a particular embodiment, the second movable part has a flexibleconstitution able to be fixed by a point situated in a central zone, andcomprises at least one contact zone and one magnet towards at least oneend. Preferably, the second movable part comprises at least one openingto a central zone.

In a preferred embodiment:

the first part comprises the first magnetizable element associated witha first contact zone and a third magnetizable element associated with athird contact zone, and

the second movable part comprises a second contact zone towards a firstend designed to be in contact with the first contact zone of the firstpart, and a fourth contact zone towards a second end designed to be incontact with the third contact zone of the first part, in a first stableposition of the movable part, the first and second contact zones aremaintained to form a closed contact and the third and fourth contactzones form an open contact, and in a second stable position of themovable part, the third and fourth contact zones are maintained to forma closed contact and the first and second contact zones form an opencontact.

Preferably, the first, second, third and fourth contact zones areelectrically connected to electrical connection means.

Advantageously, the second movable part comprises a first permanentmagnet towards the first end to operate in conjunction with the firstmagnetizable element of the first part and a second permanent magnettowards the second end to operate in conjunction with the thirdmagnetizable element of the first part.

In a preferred embodiment, the switching device comprises maintainingmeans to keep the second movable part in a third stable position whereinthe contact formed by the first and second contact zones and the contactformed by the third and fourth contact zones are open.

Preferably, the maintaining means comprise a support element in the formof a flat part arranged on the first part to receive a first side of thesecond movable part and pressure means to keep a central zone of thesecond movable part against said support element. For example, thepressure means are formed by a spring.

Preferably, the pressure means are formed by a third permanent magnetand a fourth magnetizable element arranged on the support element and onthe central zone of the movable part.

In a preferred embodiment, the switching device comprises manual ormechanical actuating means acting on the second movable part to make itchange stable state.

In a particular embodiment, the second movable part has a flexibleconstitution able to be fixed by a point situated in a central zone, andcomprises at least one contact zone and a magnet with two ends to formtwo contacts with contact zones of magnetizable elements of the firstpart, said two contacts being able to be closed simultaneously.

Advantageously, at least one magnetic or magnetizable element enables anelectric current designed to flow in at least one electrical contact tobe conducted through the material that constitutes it.

An electromagnetic relay according to the invention with at least twostable states comprising at least a first and a second electricalcontact inputs, control inputs, and at least one switching device asdefined above, the first electrical contact input being connected to thesecond movable part, the second electrical contact input being connectedto a first contact zone of the first part, and the control inputs beingconnected to at least a first electromagnetic coil arranged on at leasta first magnetizable element of the first part.

In a preferred embodiment, the relay comprises at least a secondelectromagnetic coil connected to the control inputs and arranged on atleast a third magnetizable element of the first part.

In another embodiment, the relay has at least three stable states andcomprises a third contact zone connected to a third contact input andmeans for keeping the second movable part in a third stable positionwhere the electrical contacts between the first, second and thirdcontact zones are open, the first and second electromagnetic coils beingdesigned to be commanded in attraction and repulsion to establish anelectrical contact and in double repulsion to open the contacts.

An electrical apparatus according to the invention, comprising at leasta first and a second electrical contact inputs, comprises:

at least one switching device as defined above with at least two stablepositions, the first electrical contact input being connected to thesecond movable part, the second electrical contact input being connectedto a first contact zone of the first part, and

a control circuit connected to at least a first electromagnetic coilarranged on a first magnetizable element of the first part.

In a preferred embodiment, the switching device comprises at least asecond electromagnetic coil connected to the control circuit andarranged on at least a third magnetizable element of the first part.

Advantageously, the switching device has three stable states andcomprises a third contact zone connected to a third contact input andmeans for keeping the second movable part in a third stable positionwhere the electrical contacts between the first, second and thirdcontact zones are open, the first and second electromagnetic coils beingdesigned to be commanded in attraction and repulsion to establish atleast one electrical contact and in double repulsion to open thecontacts.

In a preferred embodiment, the electrical apparatus comprises manual ormechanical actuating means acting on the second movable part to make itchange stable state.

Advantageously, the control circuit comprises at least one control inputable to receive control signals.

Advantageously, the control signals applied to the input can bepolarization signals, pulse duration signals and/or number of pulsesignals.

Advantageously, the control circuit comprises at least one remotecontrol input by communication bus to receive control signals.

Advantageously, the control circuit comprises remote control receiptmeans to receive control signals.

Advantageously, the control circuit comprises processing means toprocess control signals and to control the electromagnetic coilsaccording to said signals. Preferably, the processing means performremote control switch, time switch and/or controlled switch functions.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages and features will become more clearly apparent from thefollowing description of particular embodiments of the invention, givenas non-restrictive examples only, and represented in the accompanyingdrawings in which:

FIGS. 1 and 2 represent known switching devices of bistable relays ofthe prior art;

FIG. 3 represents a switching device according to a first embodiment ofthe invention with two stable positions;

FIG. 4 represents a switching device according to an alternative of theembodiment of FIG. 3;

FIG. 5 represents a switching device according to a second embodiment ofthe invention with three stable positions;

FIG. 6 represents a switching device according to a third embodiment ofthe invention with three stable positions;

FIG. 7 represents a switching device according to a fourth embodiment ofthe invention with three stable positions;

FIGS. 8, 9 and 10 represent three positions of a switching deviceaccording to an embodiment of the invention with three stable positions;

FIG. 11 represents a switching device according to the inventiondesigned to form part of an electrical apparatus;

FIG. 12 represents an electrical apparatus comprising a switching deviceaccording to an embodiment of the invention able to be controlled by amanual control or electromagnetic control coils;

FIG. 13 represents a switching device according to an embodiment of theinvention with two or three stable positions designed to be mounted inparticular on a printed circuit or to form part of an electricalapparatus such as a relay;

FIGS. 14 and 15 represent views of a relay according to an embodiment ofthe invention comprising a switching device according to FIG. 13;

FIG. 16 represents a diagram of an electrical apparatus comprising aswitching device according to an embodiment of the invention and acontrol circuit;

FIG. 17 represents a diagram of control of a switching device accordingto an embodiment of the invention;

FIG. 18 represents a diagram of an electrical apparatus comprising aswitching device with three stable positions according to an embodimentof the invention and a control circuit;

FIG. 19 represents a diagram of a control circuit;

FIGS. 20A, 20B, 20C, 21 and 22 represent control signals able to be usedby control circuits of switching devices according to embodiments of theinvention;

FIG. 23 represents a particular embodiment of a movable part of a deviceaccording to an embodiment of the invention;

FIG. 24 represents a switching device according to an embodiment of theinvention comprising a movable part according to FIG. 23;

FIG. 25 represents a second particular embodiment of a movable part of adevice according to an embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In a device according to an embodiment of the invention represented inFIG. 3, a first, preferably fixed, part 30 comprises a firstmagnetizable element 31 and a first contact zone 32 associated with saidfirst magnetizable element 31, and a second movable part 33 comprises asecond magnetic element 34 and a second contact zone 35 associated withsaid second magnetic element 34. Said second movable part 33 has atleast a first stable position to keep a first electrical contact 36closed between the first and second contact zones 32 and 35 and a secondstable position to keep said first electrical contact open. Actuatingmeans 37 able to be electromagnetic, and possibly manual or mechanical,enable action to be performed on the second movable part to make itchange position. The first or second magnetic element comprises at leastone permanent magnetization part to keep the first contact closed and toexert a contact pressure between the first and second contact zones.

The contact pressure is exerted by a magnetic attraction between thefirst and second magnetic elements when the movable part is in its firststable position where the first contact 36 is closed. For example, thesecond magnetic element can be a magnet 38 arranged on the movable part33, the first magnetizable element 31 being able to be made of magneticmaterial, for example soft iron. In a preferred embodiment, theactuating means comprise a first electromagnetic coil 53 to act on themagnet 38 of the second magnetic element of the movable part.

In the embodiment of FIG. 3, the first part 30 comprises a thirdmagnetizable element 39 to keep the second movable part 33 in the secondstable position. A second magnet 40 arranged on the movable part ensuresthat the latter is kept in the second stable position by a magneticattraction exerted with the third magnetizable element 39. The switchingdevice can comprise a second electrical contact 41 comprising a thirdcontact zone 42 associated with the third magnetizable element 39 and afourth contact zone 43 on the movable part 33. In this case, theactuating means comprise a second electromagnetic coil 54 to act on themagnet 40 of the second magnetic element of the movable part.

Advantageously, the permanent magnets are arranged in proximity to thecontact zones to ensure a good contact pressure. Preferably thepermanent magnetization part or the permanent magnet have a magneticinduction greater than 1 tesla with a volume smaller than 1 cubicmillimeter (mm³) for a rated current in the contacts of about 1 ampere.In this case, a device able to operate at 10 amperes can have a magnetsmaller than 10 mm³. With magnets with an induction of more than 3teslas per mm³, a switching device will have a magnet of about 3 mm³ for10 amperes.

Preferably, the movable part 33 has an elongate shape able to pivot andcomprises a contact zone and a permanent magnet at each end.

For example, to constitute a changeover switch with two contacts, in aswitching device according to an embodiment of the invention, the firstpart 30 comprises the first magnetizable element 31 associated with afirst contact zone 32, and a third magnetizable element 39 associatedwith a third contact zone 42, and the second movable part 33 comprises asecond contact zone 35, towards a first end, designed to be in contactwith the first contact zone 32 of the first part, and a fourth contactzone 43, towards a second end, designed to be in contact with the thirdcontact zone 42 of the first part. In a first stable position of themovable part, the first and second contact zones 32 and 35 aremaintained to form a closed contact and the third and fourth contactzones 42 and 43 form an open contact, and in a second stable position ofthe movable part, the third and fourth contact zones 42 and 43 aremaintained to form a closed contact and the first and second contactzones 32 and 35 form an open contact. The first, second, third andfourth contact zones are electrically connected to electrical connectionterminals by means of electrical conductors and/or the material of themagnetizable elements. The use of the magnetic or magnetizable elementsassociated with an electrical conduction function enables the volume ofthe switching device to be reduced. For example, the magnetic ormagnetizable elements can be associated with electrical conductors in asingle element or be used as conductors themselves. Thus, a magneticelement can have two types of function, advantageously, magnetic typefunctions for keeping in a stable position and for exerting a contactpressure, and electrical type functions for electrical contact with themovable part and for electrical conduction between connection terminalsand said contact.

In the embodiment of FIG. 4, the first part comprises a first electricalconductor 45A associated with a first magnetizable element 31. Toimprove rocking of the changeover switch and to ensure a second stableposition, the first part comprises a third magnetizable element 39 and asecond conductor 45B. The embodiment of FIG. 4 shows a manual actuatingdevice 50 to actuate the movable part 33 and to make it change stableposition independently from the electromagnetic interactions performedby the coils 53 and 54 acting on the magnets 40 and 38.

In the embodiment of FIG. 5, the second movable part 33 comprises afirst permanent magnet 51 towards the first end to operate inconjunction with the first magnetizable element 31 of the first part anda second permanent magnet 52 towards the second end to operate inconjunction with the third magnetizable element 39 of the first part.The device of FIG. 5 comprises electromagnetic actuating meanscomprising a first electromagnetic coil 53 wound onto the firstmagnetizable element 31 of the first part to act in attraction or inrepulsion on the second magnetic element of the second movable part 33and to perform a change of stable state of said movable part. In thisembodiment, the electromagnetic actuating means comprise a secondelectromagnetic coil 54 wound onto the third magnetizable element 39 ofthe first part to act in attraction or in repulsion on at least a secondmagnetic element of the second movable part and to make said secondmovable part change stable state. Thus, the coil 53 and magnetizableelement 31 operate in conjunction with the magnet 51 and coil 54 and themagnetizable element 39 operates in conjunction with the magnet 52 tomake the movable part 33 change state. In a first position the contactzones 32 and 35 form a closed contact whereas in a second position thecontact zones 32 and 35 form an open contact and the contact zones 42and 43 form a closed contact.

For example, the first and second electromagnetic coils 53 and 54 arecontrolled by electrical impulses to generate reverse magnetic fieldsperforming a repulsion and an attraction and to make the stable positionof the second movable part change between a first and a second stableposition.

In the embodiment of FIG. 5, the switching device also comprisesmaintaining means 55 to keep the movable part 33 in a third stableposition wherein the contact 36 formed by the first and second contactzones 32 and 35 and the contact 41 formed by the third and fourthcontact zones 42 and 43 are open.

Advantageously, the maintaining means comprise a support element 56 inthe form of a flat part or a stop arranged on the first part to receivea first side 57 of the second movable part 33 and pressure means 58 tokeep a central zone 59 of the second movable part pressed against thesupport element. For example, in FIG. 5 the pressure means are formed bya spring.

In FIG. 6, the pressure means are formed by a third permanent magnet 60arranged on the central part of the movable part and a fourthmagnetizable element 61 arranged on the support element. To actuate thesecond movable part and move it to its third stable position where thetwo contacts are open, the first and second electromagnetic coils arecontrolled by electrical impulses generating magnetic fields of the samedirection performing two repulsions.

In the embodiment of FIG. 7, manual or mechanical actuating means 50 acton the second movable part to make it change stable state. When it is inits third position, the magnet 60 operates in conjunction with thefourth magnetizable element 61 preferably comprising a flat part to holdthe movable part. In this stable position, the contact zones 35 and 43of the second movable part are not in electrical contact with thecontact zones 32 and 42 of the first part.

FIGS. 8, 9 and 10 show a switching device comprising actuation byelectromagnetic coils and a manual actuating element 50. Thus twoactuating means enable the position of the movable part 33 to bechanged. In FIG. 8, the movable part is in its third stable positionwhere the contacts 36 and 41 are open.

In FIG. 9, the first contact 36 is open and the second contact 41 isclosed by an action on the manual actuating element 50 or by electricalimpulses on the electromagnetic coils. In this case, the coil 53 hasbeen commanded to act in repulsion on the magnet 51, and the coil 54 iscommanded to act in attraction on the magnet 52.

In FIG. 10, the first contact 36 is closed and the second contact 41 isopened by an action on the manual actuating element 50 or by electricalimpulses on the electromagnetic coils. In this case, the coil 54 hasbeen commanded to act in repulsion on the magnet 52, and the coil 53 iscommanded to act in attraction on the magnet 51.

FIG. 11 represents a switching device according to the inventiondesigned in particular to form part of an electrical apparatus of smalldimensions. The first magnetizable element 31 is directly connected to aconnection terminal 44 and it receives over its length theelectromagnetic control coil 53, the first contact zone 32 at the end ofthe magnetizable element 31 is salient from the coil 53. Themagnetizable element 31 also acts as conductor between the contact zoneand the connection terminal. In this arrangement the magnetizableelement 31 has magnetic control functions of the movable part being thecore of the coil 53 and maintaining functions of the movable part byco-operating with the magnet 51, and also performs a fixed contact partfunction having a contact zone 32 and an electrical conductor functionby connecting the zone 32 to the terminal 44. Such an embodiment enablesthe size of the switching device to be considerably reduced. The thirdmagnetizable element 39 and the coil 54 are achieved and arranged in thesame manner as the element 31 and coil 53. The fourth magnetizableelement 61 can be achieved in the same manner as the first and thirdmagnetizable elements 39. It comprises a contact zone that is in contactwith the movable part 33 and operates in conjunction with the magnet 60in the central part of the movable part to ensure a contact pressure andpivoting of the movable part as well as maintaining the latter inposition. The movable part 33 can be made from conducting material suchas copper with suitable surface treatments towards the electricalcontact zone. Permanent magnets 51, 52, and 60 arranged towards the endsand the central zone of the movable part 33 are preferably stuck orcrimped onto the conducting material.

Connections of the coils 53 and 54 and of the contact conductors 45 canalso be performed by output pins or tabs 62 able to be soldered onto aprinted circuit or receive electric wires that are either soldered orconnected by spade connectors.

In FIG. 12, a switching device according to FIG. 11 is integrated in anelectrical breaking or switching apparatus. This electrical apparatuscomprises a base 63 made of insulating material to receive and securethe different elements of the switching device. In this figure, it alsocomprises a manual actuating means 50 to act manually on the movablepart. The manual actuating means 50 can also be a mechanical actuatingmeans actuated in particular by movement of an object, for example amachine or a mechanism.

FIG. 13 represents a switching device with two or three stable positionsdesigned to be mounted in particular on a printed circuit or to formpart of an electrical apparatus such as a relay. The contact conductors45 and the coil connections are terminated by connecting pins or tabs62. The conductors 45 are crimped directly onto the magnetizableelements of the first part. The fourth magnetizable element 61 also hasthe function of support element 56 to support the central part of thefixed part, in particular in its third stable position where thecontacts are open, and a function of electrical conductor 45.

In the case of a fitting as a relay, inputs 62A correspond to electricalcontact inputs and inputs 62B correspond to control inputs. A firstelectrical contact input 62A is connected to the second movable part bymeans of the fourth magnetizable element 61, a second electrical contactinput 62A is connected to a first contact zone 32 of the first part bymeans of the first magnetizable element 31, a third electrical contactinput 62A is connected to a third contact zone 42 of the first part bymeans of the third magnetizable element 39, and the control inputs 62Bare connected to the first and second electromagnetic coils 53 and 54arranged on the first and third magnetizable elements 31 and 39 of thefirst part.

FIGS. 14 and 15 represent views of a relay according to an embodiment ofthe invention comprising a switching device according to FIG. 13. Therelay comprises a support 64, for example in the form of a case, and acover 65 closing said support. Passages arranged in the case enableelectrical connection inputs 62 to pass. FIG. 14 shows an exploded viewof the elements of the switching device. The assembled relay isrepresented in the view of FIG. 15 where the elements are in place. Thisview shows advantages of the invention, in particular the reduction ofspace and volume permitted by such an arrangement. Grouping ofelectrical and magnetic functions in a single element enables theseadvantages to be achieved.

The relay of FIGS. 13, 14 and 15 can be a relay with two stablepositions or three positions depending on the control mode of the coils53 and 54. The first and second coils are commanded in attraction andrepulsion to establish an electrical contact and in double repulsion toopen the two contacts.

FIG. 16 represents a diagram of an electrical apparatus comprising aswitching device according to an embodiment of the invention and acontrol circuit 70. The electrical apparatus comprises a firstelectrical contact input 71 connected to the second movable part 33, anda second electrical contact input 72 connected to a first contact zone32 of the first part by means of the first magnetizable element 31, anda third electrical contact input 73 connected to a third contact zone 42of the first part by means of the third magnetizable element. Thecontrol circuit 70 is connected to a first and second electromagneticcoil 53 and 54 respectively arranged on the first and third magnetizableelement 31 and 39 of the first part. In the embodiment of FIG. 16, thecoils 53 and 54 are connected in series to control movement of themovable part in attraction and repulsion. The movable part 33 cancomprise magnets in the material that composes it. Manual or mechanicalactuating means 50 can also act on the second movable part to make thelatter change stable state. The control circuit 70 comprises controlinputs 74 able to receive control signals.

The control signals applied to the control inputs 70 can be inparticular polarization signals, pulse duration signals and/or number ofpulse signals.

In the diagram of FIG. 17, the coils 53 and 54 are connected with thecontrol circuit to the inputs 74. In this diagram, the apparatus thenreceives control signals in the form of electrical pulses supplied by apush-button 75 connected between the inputs 74 and an electric powersource 76, for example a mains power distribution system. The controlcircuit can act on the coils by simple switch or remote-controlledreversing switch commands or, for example, by more complex functionssuch as remote control switch, time delay device, or electric timeswitch functions.

FIG. 18 represents a diagram of an electrical apparatus comprising aswitching device with three stable positions such as the one describedfor FIGS. 8 to 10 and a control circuit 70. The coils 53 and 54 areconnected to the control circuit to be able to be commanded inattraction and repulsion to establish at least one electrical contact 36or 41 and in double repulsion to open said electrical contacts. A magnet60 and a fourth magnetizable element 61 enable the movable part to bekept in the open contacts position.

In FIG. 19, a diagram of a control circuit shows different possibilitiesof receipt of control signals. The control circuit 70 comprises a powersupply circuit connected between power supply inputs 78 and a processingcircuit 79. The control circuit 70 controls the coils 53 and 54according to control signals received in particular on control inputs74.

The control circuit 70 can also comprise a remote control circuitconnected to the processing circuit and receiving control signalssupplied via a communication bus 81 and/or a remote control receiver.

FIGS. 20A, 20B, 20C, 21 and 22 represent control signals able to be usedby control circuits of switching devices according to embodiments of theinvention. In FIG. 20A a signal 90 of negative polarity can command thecontrol circuit 70 to position the switching device in a first stableposition where a first contact 36 is established. In FIG. 20B a signal91 of positive polarity can command the control circuit 70 to positionthe switching device in a second stable position where a second contact41 is established. In FIG. 20C a signal 92 having negative and positivepolarities can command the control circuit 70 to position the switchingdevice in a third stable position where the contacts 36 and 41 areopened in particular by double repulsion commands on the coils 53 and54. FIG. 21 represents control signals 93 by pulse duration, and FIG. 22represents control signals 94 by number of pulses.

FIG. 23 represents a particular embodiment of a second movable part 33having a flexible constitution able to be fixed by a point 100 situatedin a central zone, and comprises at least one contact zone 35 and/or 43and a magnet 51 and/or 52 towards at least one end. The second movablepart comprises one or two openings towards a central zone to improve theflexibility and movement between the stable positions. The body of themovable part can advantageously be formed by a material such as brass orsteel.

FIG. 24 represents a switching device comprising a second movable partaccording to FIG. 23. The point 100 of the central zone is fixeddirectly onto the support element 56. In this embodiment, the flexibleconstitution of the second movable part also enables the two contacts 36and 41 to be closed simultaneously. Thus, the contacts can be opened orclosed independently, in particular by electromagnetic controls.

In FIG. 25, a second movable part 33 is composed of a materialcomprising a mainly permanent magnetization part, for example alongitudinal magnet 103 comprising contact pads at each end.

In the embodiments described above, the electrical contact zones can beachieved by deposits of suitable metal or by adding contact pads ofsmall thickness. The magnets can have different shapes and be fixed ontofixed or movable parts of the magnetic elements. The magnetic ormagnetizable elements can also be covered with material depending on theintensity of the current which has to flow through the contacts. Thecurrent can reach several amperes in a small volume.

The electrical apparatuses able to comprise a switching device accordingto the invention can be of very different kinds, for example low or highpower switches, circuit breakers, auxiliary contacts, or contactscontrolled by mechanisms or manually.

1. An electrical switching device comprising At least one electricalcontact able to be kept in a stable position by magnetic means, whichcontact comprises: at least a first part comprising a first magnetizableelement and a first contact zone associated with said magnetizableelement, a second moveable part comprising a first magnetic element anda second contact zone associated with said first magnetic element, thesecond movable part having a first stable position wherein a firstelectrical contact is kept closed between the first and second contactzones and a second stable position wherein said first electrical contactis kept open, and electromagnetic actuating means acting on the secondmovable part for causing the latter to change position and comprising afirst electromagnetic coil wound onto said a first magnetizable elementof the first part for attracting or repelling a first magnetic elementof the second movable part and for changing the stable state of saidmovable part, the first magnetizable element or the first magneticelement comprising a permanent magnetization part located in proximityto a contact zone for keeping the first electrical contact closed andfor exerting a contact pressure between the first and second contactzones by a magnetic attraction exerted directly between the firstmagnetizable element and the first magnetic element when the movablepart is in its first stable position.
 2. The switching device accordingto claim 1, wherein the electromagnetic actuating means comprise asecond electromagnetic coil wound onto at a second magnetizable elementof the first part for attracting or repelling the first magnetic elementof the second moveable part and for changing the stable state of saidsecond movable part.
 3. The switching device according to claim 2,wherein the first and second electromagnetic coils controllable byelectrical pulses to generate reverse magnetic fields for changing thestable position of the second movable part change between first and asecond stable positions closing at least one electrical contact betweena contact zone of the first part and a contact zone of the secondmovable part.
 4. The switching device according to claim 2, wherein thefirst and second electromagnetic coils are controllable by electricalpulses to generate magnetic fields of the same direction for positioningthe second movable part in a third stable position wherein the contactzones of the second movable part are not in electrical contact with thecontact zones of the first part.
 5. The switching device according toclaim 1, wherein the first part comprises a second magnetizable elementfor keeping the second movable part in the second stable condition. 6.The switching device according to claim 1, wherein the second movablepart comprises at least one permanent magnet located in proximity to acontact zone.
 7. The switching device according to claim 1, wherein thesecond movable part comprises a material comprising a mainly permanentmagnetization part.
 8. The switching device according to claim 1,wherein the permanent magnetization part has a magnetic inductiongreater than 1 tesla.
 9. The switching device according to claim 1,wherein the second movable part has an elongate shape, is able to pivotsand comprises at least one contact zone and one magnetic attraction zonetowards at least one end thereof.
 10. The switching device according toclaim 9, wherein the second movable part comprises at least one contactzone at a first end thereof and at least one permanent magnet at asecond end thereof.
 11. The switching device according to claim 1,wherein the second movable part is flexible, is able to be fixed by apoint situated in a central zone thereof, and comprises at least onecontact zone and one magnet towards at least one end thereof.
 12. Theswitching device according to claim 11, wherein the second movable partcomprises at least one opening in said central zone.
 13. The switchingdevice according to claim 1, wherein: the first part comprises the firstmagnetizable element associated with a first contact zone and a secondmagnetizable element associated with a third contact zone, and thesecond movable part comprises a second contact zone towards a first enddesigned to be in contact with the first contact zone of the first part,and a fourth contact zone towards a second end designed to be in contactwith the third contact zone of the first part, so that when in a firststable position of the movable part, the first and second contact zonesform a closed contact and the third and fourth contact zones form anopen contact, and in a second stable position of the movable part, thethird and fourth contact zones form a closed contact and the first andsecond contact zones form an open contact.
 14. The switching deviceaccording to claim 13, wherein the first, second, third and fourthcontact zones are electrically connected to electrical connection means.15. The switching device according to claim 13, wherein the secondmovable part comprises a first permanent magnet towards the first endthereof for operating in conjunction with the first magnetizable elementof the first part, and a second permanent magnet towards the second endthereof for operating in conjunction with the second magnetizableelement of the first part.
 16. The switching device according to claim13, comprising maintaining means for keeping the second movable part ina third stable position wherein both the contact formed by the first andsecond contact zones and the contact formed by the third and fourthcontact zones are open.
 17. The switching device according to claim 16,wherein the maintaining means comprise a support element which includesa flat part located on the first part for receiving a first side of thesecond movable part, and pressure means for keeping a central zone ofthe second movable part in contact with said support element.
 18. Theswitching device according to claim 17, wherein the pressure means is aspring.
 19. The switching device according to claim 17, wherein thepressure means comprise a third permanent magnet and a thirdmagnetizable element located on the support element and on the centralzone of the movable part.
 20. The switching device according to claim 1,comprising actuating means acting on the second movable part for causingit to change stable state.
 21. The switching device according to claim1, wherein the second movable part is flexible, is able to be fixed by apoint situated in a central zone, and comprises at least one contactzone and a magnet having two ends for forming two contacts with contactzones of magnetizable elements of the first part, said two contactscapable of being closed simultaneously.
 22. The switching deviceaccording to claim 1, wherein said at least one magnetizable element issufficiently electrically conductive to permit an electric currentdesigned to flow in at least one electrical contact to be conductedthrough it.
 23. An electromagnetic relay having at least two stablestates comprising a first and second electrical contact inputs andcontrol inputs, at least one switching device according to claim 1, thefirst electrical contact input being connected to the second movablepart, the second electrical contact input being connected to a firstcontact zone of the first part, and the control inputs being connectedto at least a first electromagnetic coil located on at least a firstmagnetizable element of the first part.
 24. A relay according to claim23, comprising at least a second electromagnetic coil connected to thecontrol inputs and located on at least a second magnetizable element ofthe first part.
 25. A relay according to claim 23, having at least threestable states and comprising a third contact zone connected to a thirdcontact inputs and means for keeping the second movable part in a thirdstable position wherein the electrical contacts between the first,second, and third contact zones are open, the first and secondelectromagnetic coils for attracting and repelling to establish anelectrical contact and for double repelling to open the contacts.
 26. Anelectrical apparatus comprising at least first and a second electricalcontact inputs, comprising: at least one switching device according toclaim 1 having at least two stable positions, the first electricalcontact input being connected to the second movable part, the secondelectrical contact input being connected to a first contact zone of thefirst part, and a control circuit connected to at least a firstelectromagnetic coil located on a first magnetizable element of thefirst part.
 27. An electrical apparatus according to claim 26, whereinthe switching device comprises at least a second electromagnetic coilconnected to the control circuit and located on at least a secondmagnetizable element of the first part.
 28. An electrical apparatusaccording to claim 26, wherein the switching device has three stablestates and comprises a third contact zone connected to a third contactinput and means for keeping the second movable part in a third stableposition wherein the electrical contacts between the first, second, andthird contact zones are open, the first and second electromagnetic coilsfor attracting and repelling to open the contacts.
 29. An electricalapparatus according to claim 26, comprising actuating means for actingon the second moving part to make it change stable state.
 30. Anelectrical apparatus according to claim 26, wherein the control circuitcomprises at least one control input for receiving control signals. 31.An electrical apparatus according to claim 30, wherein the controlsignals applied to the input are selected from the group consisting ofpolarization signals, pulse duration signals, and number of pulsesignals.
 32. An electrical apparatus according to claim 26, wherein thecontrol circuit comprises remote control input by communication bus forreceiving control signals.
 33. An electrical apparatus according toclaim 26, wherein the control circuit comprises remote control receiptmeans for receiving control signals.
 34. An electrical apparatusaccording to claim 26, wherein the control circuit comprises processingmeans for processing control signals and to for controlling theelectromagnetic coils according to said signals.
 35. An electricalapparatus according to claim 34, wherein the processing means is forperforming at least one function selected from the group consisting ofremote control switch, timer and controlled switch functions.